There has been known so far such a method which comprises the steps of placing an object to be sanitized into an infrared ray irradiating apparatus in which a ceramic heater is provided as an infrared ray irradiation body and operating the ceramic heater to irradiate the object with infrared rays containing plenty of far-infrared rays while ventilating the air within the infrared ray irradiating apparatus, thereby heat-sterilizing the object (Japanese Laid-Open Patent Gazette No. 50-685).
The above-noted prior-art apparatus utilizes the ceramic heater as the infrared ray irradiating bodies so that a heating temperature is as high as, for example, 100.degree. to 450.degree. C. Such high temperature exerts a harmful influence upon the object to be sanitized, causing the object to be sanitized to be burned. Therefore, the ceramic heater and the object to be sanitized must be cooled by air and water, which provides a large-sized and expensive apparatus.
It is frequently observed that the large-sized apparatus heats extra portion of the object to be sanitized. This is uneconomical and makes the temperature administration difficult. Further, the ceramic heater can not directly oppose the object to be sanitized or can not be placed closest to the object to be sanitized, which limits the application field of the sanitation device. Furthermore, the temperature exerts a harmful influence upon the object to be sanitized so that the object to be sanitized is damaged by burning or the object to be sanitized is heated too much. There is then a risk that the user will be burned.